The present invention relates generally to floating covers, particularly of the type to be used over large reservoirs.
Floating covers for contained fluids, generally speaking, are well known in the prior art. Some of this art is directed towards fluids contained within a tank or vessel rather than a fluid to be contained in a reservoir. Numerous patents such as U.S. Pat. Nos. 3,228,702; 1,775,758; 1,712,321; 3,343,708; 3,016,814 are directed towards providing seals for floating coverings that engage the sides of a suitable tank. Similarly, U.S. Pat. Nos. 3,159,301 and 3,557,994 are directed towards floating diaphragms adapted to be used in various pressure tanks. Other non-floating types of diaphragm covers for tanks are disclosed in U.S. Pat. Nos. 1,917,623 and 3,028,040. However, all of such prior art is directed towards floating structures that are contained within a substantially enclosed housing such as a tank or vessel. Such floating covers are not exposed to the adverse environmental conditions such as wind, ice and water accumulations on the surfaces thereof as well as the problems incumbent in providing floating sturctures for large expansive reservoirs rather than comparatively small storage tanks.
Floating covers, such as disclosed in U.S. Pat. Nos. 3,462,040; 3,592,009; and, 3,740,902, have long been in use. However, a recurring problem that has plagued reservoir covers of the prior art is how to control the tension of the floating cover on the fluid while accommodating fluid elevational changes in a reservoir having sloping or tapered surfaces adjacent reservoir peripheries. In U.S. Pat. Nos. 2,986,302 and 3,079,030, movable segmented sections are used to support the floating cover as the fluid level experiences elevational variations. U.S. Pat. No. 3,330,118 discloses the use of a plurality of circular floaters for supporting the cover of a sunken tank as the fluid varies in elevation while U.S. Pat. No. 2,970,716 uses multiple sections in combination with pontoons to support the floating roof for an oil storage reservoir.
U.S. Pat. No. 3,815,367 discloses the use of a complex tensioning line-arrangement for providing for the proper tension of a floating cover assembly for a reservoir to insure biasing thereof. Further, the present inventor disclosed in U.S. Pat. Nos. 3,313,443 and 3,667,641 floating cover arrangements which provide for a variety of drain configurations to prevent unwanted accumulation of liquid on the upper surface of such a liquid storage reservoir cover in an effort to prevent damage due to the weight of unwanted liquid on the upper surface of the cover and/or the detrimental environmental effects due to freezing and the like. Further, U.S. Pat. No. 3,736,754 discloses a combination two-cover assembly wherein one cover is used to float on the surface of the stored liquid while another roof is inflated thereover for protection of the floating roof. This dual roof assembly not only is expensive but requires maintenance on both the floating cover as well as the inflatable roof.
Not only is it important that a floating cover have the proper tension thereon to prevent damage thereto as a result of high wind and/or water accumulations thereon, but also it is important to provide for ease in reservoir maintenance thereof without necessitating removal of the cover. Typically, prior art repairs and other reservoir maintenance was accomplished by divers submerged in the reservoir fluid below the reservoir cover. However, no provisions are made in the prior art for providing an effective system of maintenance and repair of both the floating cover as well as the storage reservoir in combination with means for compensating for elevational changes of the fluid within the reservoir while providing the necessary tension on the reservoir cover.
Also, in the prior art, flexible and/or inflatable structures have been used for a wide variety of applications which include use in a variety of shelter or building configurations such as those disclosed in U.S. Pat. Nos. 3,924,363; 3,626,836; and 3,885,360 as well as an inflatable covering for swimming pools as disclosed in U.S. Pat. No. 3,918,221 and collapsible dams and damming methods as disclosed in U.S. Pat. No. 3,834,167.
Although these relate generally to inflatable structures, these are of little consequence in considering the requirements that must be met by a reservoir cover that must not only float on the surface of the reservoir fluid having a required tensioning thereof but also have appropriate provisions for ease in reservoir or cover maintenance.